The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
Currently, the vast majority of passenger car and light truck automatic transmissions utilize a plurality of planetary gear assemblies and sequenced, hydraulically operated clutches and brakes to provide four, five, six or more forward speeds or gears and reverse. The hydraulic fluid which circulates in the transmission is drawn from a sump, pressurized by a gear, vane or gerotor pump and provided to a control valve body having a plurality of control valves which direct the pressurized hydraulic fluid to the appropriate clutch and brake actuator at the appropriate time to achieve a desired gear.
The hydraulic pump is typically mounted around and driven by the shaft coupling the output of the torque converter with the input of the transmission. As such, the pump requires a separate, dedicated housing disposed about the transmission input shaft axis. Moreover, this housing occupies and may increase the axial length of the transmission, never a desirable outcome. Additionally, since it is well above the sump, it is necessary to include a suction line which communicates with the sump as well as a return or supply line which communicates with the valve body. Not only does the difference in height occasionally present priming issues but also the fluid lines result in pressure and energy losses. Finally, the weight and cost of such a stand-alone component is undesirable.